• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    Equipment for the pollution prevention of a nuclear reactor vessel (4) whose lid (6) has been disassembled, in particular for fuel loading, the risk of pollution arising in particular from the decontamination of the parols (7a) of the swimming pool surmounting the reactor and emptied of its water, this equipment comprising a protective screen constituted by a skirt (9) of flexible material, the upper part of the skirt being designed to be fixed so as to surround the upper part of the lid (6 ) while it is placed above the tank, the skirt can hang down by surrounding the lid and the top of the tank, and the bottom portion (9a) of the skirt is tightly sealed against the periphery of the tank (4).
    公开号:BE1018054A3
    申请号:E2008/0166
    申请日:2008-03-20
    公开日:2010-04-06
    发明作者:Serge Reviron
    申请人:Endel Sociutu Par Actions Simplifiue；
    IPC主号:
    专利说明:

    PROTECTIVE EQUIPMENT AGAINST THE POLLUTION OF A NUCLEAR REACTOR TANK, AND METHOD OF IMPLEMENTING SUCH EQUIPMENT.
    The invention relates to protective equipment against pollution of a nuclear reactor vessel whose lid has been disassembled, in particular for a fuel loading, the risk of pollution resulting in particular from the decontamination of the walls of the swimming pool overcoming the reactor and emptied of its water, this equipment including a screen to cover the top of the tank.
    PWR PWRs are usually shut down every 12 months for partial fuel replacement and maintenance work. For these operations, the pool that surmounts the reactor is emptied of its water and the lid of the tank is removed and deposited, by a lifting means, away from the tank. The lower area of the pool, adjacent to the tank, has a radioactive contamination that should be eliminated to the maximum before maintenance staff intervenes in the bottom of the pool around the tank. The decontamination of the lower part of the walls of the pool is usually done by spraying water under pressure by technicians equipped with special clothing. During this decontamination, it is essential to avoid pollution of the reactor vessel by the water sprayed on the walls of the pool.
    Until now, to allow the operation of decontaminating the walls of the empty pool, without causing pollution of the tank, a protective cap is sealingly attached to the tank during this decontamination operation. When the operation is complete, the cap is disassembled and then evacuated to undergo itself a decontamination. The reactor lid is then replaced.
    All these operations are relatively long and costly because the loss of electricity production of a nuclear power plant equipped with the reactor depends directly on the duration of these operations.
    The object of the invention is, above all, to provide pollution protection equipment for a nuclear reactor vessel which makes it possible to carry out the decontamination of the walls of the empty pool more simply and quickly while ensuring effective protection. of the reactor vessel.
    According to the invention, protective equipment against the pollution of a nuclear reactor vessel whose lid has been removed, of the kind defined above, is characterized in that: - the protective screen is constituted by a skirt material flexible flexible, - the upper part of the skirt is intended to be fixed so as to surround the upper part of the tank lid while it is placed above the tank, the skirt can hang down by surrounding the lid and the top of the tank, and the lower part of the skirt is tightly sealed against the periphery of the tank.
    Preferably, the equipment comprises an inflatable seal disposed around the entire periphery of the tank between a flange of the lid and a flange of the tank, this seal being surrounded by the lower part of the skirt.
    Advantageously, the skirt is consumable, to be sent to waste after use. The inflatable seal is also consumable, to be sent to waste after use.
    The skirt may be a plastic sheet. The inflatable seal may be made of plastic material, advantageously Prodene 346.
    The invention also relates to a method for implementing the protective equipment as defined above, this method being characterized in that: the upper part of the skirt is attached so as to surround the upper part of the skirt. lid, suspended on a lifting means, so that it can hang downwards, - the tank lid, surrounded by the skirt, is placed above the tank and placed on it, - the lower part of the skirt is tightly sealed against the periphery of the flange of the tank next to that of the lid, - decontamination of the walls of the pool is carried out, - the skirt is removed and discharged to the waste, - any maintenance work is carried out, and the final assembly of the lid on the tank is carried out.
    Preferably, an inflatable seal is disposed all around the vessel between the lid and the tank, the seal is inflated to establish a seal during decontamination, the seal is then surrounded by the skirt, and after operation the seal is deflated and put to waste.
    The invention consists, apart from the arrangements set out above, in a number of other arrangements which will be more explicitly discussed below with respect to an embodiment described with reference to the accompanying drawings, but which is in no way limiting.
    On these drawings:
    Fig.1 is a simplified schematic vertical section, with external parts, of a nuclear reactor and its building.
    Fig.2 is a schematic vertical simplified section of the reactor vessel whose lid has been removed and on which is installed a protective cap for decontamination of the pool, according to the state of the art.
    Fig.3 is a schematic vertical section of the nuclear reactor vessel with its cover shown externally.
    Fig.4 is an enlarged external view of the reactor vessel cover on which is installed a protective skirt according to the invention, with parts torn off.
    FIG. 5 is a diagrammatic vertical section of the tank with the cover shown externally placed on the tank, the protective skirt being tightened around the tank for the decontamination operation, and
    Fig.6 is a schematic vertical section on a larger scale of a portion of the lid and the tank on which is installed the protective equipment according to the invention.
    Referring to FIG. 1 of the drawings, it is possible to see, summarily represented, a PWR nuclear power reactor 1 of a power generation plant. The reactor 1 is surrounded by a building 2 which comprises, at the top, a lifting means 3 constituted by a swing bridge. The reactor 1 comprises a tank 4 installed in a well 5 and sealed in operation by a tank lid 6. The tank 4 is surmounted by a pool 7 which is filled with water during operation of the reactor.
    To proceed with the nuclear fuel replacement operations A, it is necessary to empty the pool 7 of its water, then to remove the tank lid 6 away from the tank 4. For various work, including work of maintenance, personnel must descend into the empty pool 7 and work around the open tank 4. Then, the lid 6 is again attached to the tank.
    The dosimetric environment, especially because of the contamination of the lower walls 7a of the pool, is such that a decontamination of this area must be carried out to allow the staff, equipped with adequate clothing, to stay sufficient time around the tank to do the necessary work. The decontamination operation of the lower zone 7a of the pool and the environment of the open vessel 4 can only be carried out under the following conditions: no foreign body intrusion into the tank 4; - No shock on the joint plane of the tank 4 with its lid 6 deposited; - No mixing between the decontamination water and the primary circuit of fluid flowing in the tank 4, preventing any entry of the decontamination water into the tank 4.
    The decontamination of the zone 7a of the pool is carried out by spraying water under pressure by specially equipped persons with protective clothing, which handle water lances under pressure.
    According to the state of the art, as illustrated in FIG. 2, the protective equipment of the tank 4, whose lid has been removed, comprises a rigid cap 8 sealingly installed on the upper part of the tank 4. The cap 8 must therefore be placed and fixed on the tank 4 before the decontamination operation of the zone 7a of the walls of the pool. The cap 8 must then be deposited and evacuated, to undergo itself a decontamination since it will have been in contact with the decontamination water walls 7a. The dimensions of the cap 8 are several meters, both in diameter and height, so that the handling of this cap 8 requires the use of the lifting means 3 and that the storage of this cap 8, in particular for its decontamination after use, requires a lot of space.
    Also, the decontamination of the walls 7a, according to the state of the art, take a long time, resulting in a long period of interruption of reactor production.
    The use of the protective cap 8 requires the realization of a set of related operations some of which are critical: - the opening and closing of a hardware access buffer for evacuation of the protective cap after use ; - Making the cap in two parts, because of its size, and assembling these two parts of the cap for its installation, while the heart of the reactor vessel is loaded; - Installation of so-called "light" protections, put in place on the joint plane of the tank. These protections can be in the form of manually manipulated plastic sectors. Their placement before decontamination requires the action of an agent in a high radiation zone.
    After decontamination of the walls 7a, the cap 8 is deposited and the reactor lid 6 is fixed on the tank 4 as shown in FIG.
    In order to overcome some of these operations, to make the intervention faster, according to the invention, the protective screen of the tank is constituted by a skirt 9 (FIG. 4) of flexible, flexible material , in particular made from a sheet of plastic material.
    The upper part of the skirt is provided to be fixed so as to surround the upper part of the lid 6 while it is deposited, away from the tank (Fig.4), on a support B.
    The skirt 9 is suspended from the lid by hooks 10 placed in place with suitable telescopic poles. These hooks pass through the skirt by metal inserts, in particular in the form of eyelets fixed in the skirt. An adhesive is put in place around the hooks to eliminate the risk of loss of them. The skirt is temporarily rolled on itself, in the lower part 9a, as shown in Fig.4, not to exceed the nominal size of the cover 6 during handling.
    The skirt 9 may be made in two or three parts connected, in a sealed manner, by an adjustment device (not shown in the drawing) repositionable at the passage of guide columns used during handling above the tank 4 .
    The skirt 9 is made of a material which makes it possible to give this skirt the following characteristics: - sealing; - high resistance to tearing; - excellent compactability.
    Before placing the lower portion 9a of the skirt around a flange 12 of the tank adapted to cooperate with a corresponding flange 13 of the lid, an inflatable O-ring 14 is provided under the flange 13 of the lid, and the seal 14 is held by its elasticity around the flange 13, in particular around pegs 13a (FIG. 6) provided in vertical housings of the flange 13 and protruding vertically downwards to enter corresponding housings of the flange 12 of the tank and ensure the centering of the lid on the tank. The seal 14 can also be held by adhesives that ensure its position during the handling phases of the lid.
    The lid 6, equipped with the skirt 9, is placed by the lifting means 3 above the tank 4 and lowered to rest on the tank, without being fixed permanently.
    Once the lid 6 is placed on the tank 4, as illustrated in FIGS. 5 and 6, the seal 14 is positioned between the outer perimeter of the lower part of the flange 13 of the lid 6 and the flange 12 of the tank . An inflation, preferably in air, of the O-ring 14 is achieved by means of a specific adapter which makes it possible to limit the rise in pressure and to be sure not to exceed the elastic limit of the seal material.
    The lower part 9a of the skirt is then unwound and tightly tightened around the tank, using an integrated rope system 11 providing circumferential clamping.
    The seal 14 formed by an inflatable torus, is made from a material: - flexible; - lightweight ; - having excellent compactability.
    The inflatable seal 14 is advantageously made of plastic, in particular Prodene 346. A specific valve is provided on the seal 14 to allow rapid deflation.
    The seal 14 has the following mechanical properties: homogeneous deformation; - resistance to bursting; - compactable; - no halogen ion; - hard enough to withstand the pressure; - thin enough to ensure a good seal and prevent leakage between lid and tank; - Elasticity sufficient to adapt to the radii of the flange of the tank.
    The staff ensuring the implementation of the skirt 9 and the seal 14 is equipped with a ventilated protective suit. The inner radius of the seal 14 is adapted to that of the lid and the tank and may be of the order of two meters forty (the perimeter being fourteen meters) or more. The average diameter of the toric section, once inflated, may be of the order of 60 mm.
    The inflatable seal 14 is provided to promote its setting in position between the flanges 12 and 13 of the tank and the lid. The seal contact with the flanges must be continuous on the periphery.
    The double protection provided by the skirt 9 and the seal 14 allows an absolute cleanliness of the joint planes of the tank and the lid by avoiding any foreign body and any trace of water at these joint planes.
    The skirt 9 also provides protection of the tank lid 6 against the protections generated during the decontamination of the pool walls; it is a protection against both contamination and corrosion.
    The sealing at the joint plane of the tank is ensured in the best conditions during the decontamination of the walls of the pool.
    The implementation of the equipment according to the invention during a replacement operation of the nuclear fuel in the tank 4 is as follows.
    After stopping the reactor, the pool 7 is emptied of its water and the lid 6 is detached from the tank 4 and removed from this tank using the lifting means 3. These operations can be controlled remotely, as the replacement of the nuclear fuel in the tank 4.
    Maintenance and verification operations then require the intervention of personnel in the bottom of the pool 7 emptied, around the tank.
    The decontamination operation of the walls 7a of the pool can be performed quickly by avoiding any pollution of the tank 4 with the protective equipment of the invention.
    As illustrated in FIG. 4, while the cover 6 has been removed from the tank 4 and installed on a temporary support B away from this tank, in the building 2, the skirt 9 is suspended, at the top, on all around the lid. The inflatable O-ring 14 is arranged on the flange 13 of the lid and is held by its elasticity around it and pins 13a.
    The seal 14 is not yet inflated.
    The lifting means 3 then ensures the displacement of the lid 6 to bring it above the tank 4 by engaging guide means provided for this purpose (not shown).
    Personnel equipped with a ventilated protective suit then down into the pool 7. The seal 14 is positioned between the outer perimeter of the lower part of the flange 13 of the lid and the flange 12 of the tank. The lid is placed on the tank so that the weight of the lid is no longer supported by the lifting means 3. The inflation of the seal 14 is then made which allows a continuous contact of the seal 14 with the flanges 12 and 13 and excellent sealing.
    The lower part of the skirt 9 is then unwound so as to surround the seal 14. The bottom of the skirt is tightly sealed with the aid of the rope 11 around the flange 12 of the tank.
    During the establishment of the skirt 9 and the seal 14 on the cover a check is made concerning: - the resistance to pressure of the seal 14; - provisional fixing of elements for the handling phase.
    Once the lid is placed on the tank, a check is made to ensure the correct position of the elements: seal and skirt, as well as the required inflation of the seal.
    These different operations could be done very quickly.
    The staff at the bottom of the pool then proceeds to decontaminate the walls 7a of the pool and the bottom with jets of liquid under pressure. The protective equipment of the invention prevents any pollution of the tank by the liquid which is discharged to the waste.
    When the decontamination operation is completed, the elements of the protective equipment, namely the skirt 9 and the gasket 14, are evacuated in the form of compactable waste.
    The lower portion 9a of the skirt 11 is loosened and disengaged from the tank 12 to allow access to the seal 14. It is deflated quickly thanks to a rapid relief valve which limits the exposure time. The seal 14 is then cut and removed.
    The skirt 9 is unhooked using telescopic poles. It is then disposed of as waste.
    The sorting of contaminated materials is done at the source. The metallic elements are extracted from the compactable elements.
    "
    At the time of disposal of the waste formed by the seal 14 and the skirt 9, a visual check of cleanliness is performed to ensure the absence of traces of water or foreign body around the lid.
    The decontamination of the walls 7a performed, it is now possible for the staff to ensure the maintenance and the final closure of the tank to go down and stay for some time, with a protective suit, in the pool 7.
    The protective equipment according to the invention is lighter and easier to handle than the equipment proposed according to the state of the art. The equipment according to the invention is put in place directly on the lid of the tank, which makes it possible to carry out the intermediate operations in complete safety and to significantly reduce the duration of the intervention.
    The equipment according to the invention can reduce by several hours, of the order of six hours or more, the duration of the intervention for the replacement of fuel.
    Dosimetric exposure of workers is reduced by a simplified procedure.
    The volume of waste generated is limited by the design of this custom-made equipment with easily compactable and shredded materials.
    权利要求:
    Claims (9)
    [1]
    1. Equipment for the protection against pollution of a nuclear reactor vessel, the lid of which has been disassembled, in particular for fuel loading, the risk of pollution resulting in particular from the decontamination of the pool walls surmounting the reactor and emptied of its water, equipment that includes a screen to cover the top of the tank, characterized in that: - the protective screen is constituted by a skirt (9) of flexible material, - the upper part of the skirt is intended to be fixed so as to surround the upper part of the tank lid (6) while it is placed above the tank, the skirt being able to hang downwards by surrounding the lid and the top of the tank, - and the part bottom (9a) of the skirt is tightly sealed against the periphery of the tank (4).
    [2]
    2. Equipment according to claim 1, characterized in that it comprises an inflatable seal (14) disposed around the entire periphery of the tank (4) between a flange (13) of the lid and a flange (12) of the tank, this seal being surrounded by the lower part (9a) of the skirt.
    [3]
    3. Equipment according to claim 1 or 2, characterized in that the skirt (9) is consumable, to be sent to the waste after use.
    [4]
    4. Equipment according to claim 2, characterized in that the inflatable seal (14) is consumable, to be sent to the waste after use.
    [5]
    5. Equipment according to any one of the preceding claims, characterized in that the skirt (9) is a sheet of plastic material.
    [6]
    6. Equipment according to claim 2 or 4, characterized in that the inflatable seal is plastic.
    [7]
    7. Equipment according to claim 6, characterized in that the inflatable seal is Prodène 346.
    [8]
    8. A method for implementing an equipment according to any one of the preceding claims to protect from pollution a tank (4) nuclear reactor whose cover is disassembled, particularly for a fuel loading, when the decontamination of the walls of the swimming pool emptied of its water surmounting the reactor, characterized in that: the upper part of the skirt (9) is attached so as to surround the upper part of the lid, suspended on a lifting means, in order to to be able to hang downwards, - the tank lid (6), surrounded by the skirt, is placed above the tank and placed on it, - the lower part (9a) of the skirt is clamped so that sealed against the periphery of the flange of the tank next to that of the lid, - the decontamination of the walls (7a) of the pool is carried out, - the skirt (9) is removed and discharged to the waste, - the possible maintenance work is made, and the final assembly of the lid on the tank is carried out.
    [9]
    9. A method according to claim 8, characterized in that an inflatable seal (14) is disposed around the entire periphery of the tank between the lid (6) and the tank (4), the seal (14) is inflated to establish a seal during decontamination, the seal is then surrounded by the skirt (9), and after operation the seal is deflated and put to waste.
    类似技术:
    公开号 | 公开日 | 专利标题
    US3167209A|1965-01-26|Flexible tank liner
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    EP0156689B1|1988-09-28|Fast nuclear reactor with suspended main vessel and lid
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    FR2649824A1|1991-01-18|Packaging for storage and transport of fissile materials
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    同族专利:
    公开号 | 公开日
    FR2915308A1|2008-10-24|
    FR2915308B1|2009-06-26|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US3812008A|1970-05-20|1974-05-21|E Fryer|Seal ring for nuclear reactors|
    US3809608A|1972-05-10|1974-05-07|Westinghouse Electric Corp|Reactor vessel annealing apparatus|
    JPS585400B2|1975-09-19|1983-01-31|Hitachi Ltd|
    DE4332882A1|1993-09-21|1995-03-23|Neschan Prof Dr Neschanjan|Device for radiation protection shielding of the water surface during the cutting of irradiated reactor parts under water|
    KR0150110B1|1995-04-21|1998-12-15|이호림|Permanent pool cavity seal for nuclear reactor|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    FR0702931|2007-04-23|
    FR0702931A|FR2915308B1|2007-04-23|2007-04-23|PROTECTIVE EQUIPMENT AGAINST THE POLLUTION OF A NUCLEAR REACTOR TANK, AND METHOD OF IMPLEMENTING SUCH EQUIPMENT.|
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